Self-propelled nanomotors use chemical energy to produce directed motion. Like many molecular motors they suffer strong perturbations from the environment in which they move as a result of thermal fluctuations and do not rely on inertia for their propulsion. Such tiny motors are the subject of considerable research because of their potential applications, and a variety of synthetic motors have been made and are being studied for this purpose. Chemically powered self-propelled nanomotors without moving parts that rely on asymmetric chemical reactions to effect directed motion are the focus of this article. The mechanisms they use for propulsion, how size and fuel sources influence their motion, how they cope with strong molecular fluctuations, and how they behave collectively are described. The practical applications of such nanomotors are largely unrealized and the subject of speculation. Since molecular motors are ubiquitous in biology and perform a myriad of complex tasks, the hope is that synthetic motors might be able to perform analogous tasks. They may have the potential to change our perspective on how chemical dynamics takes place in complex systems.

It is shown that in systems with time-dependent and/or spatially nonuniform temperature T(t, r), the diffusion(Brownian motion) is anomalous (AD). A few examples of simple arrangements, easy for experimental realization, are discussed in detail. Proposed measurements will enable also the observation of transitions from normal to anomalous diffusion. New effects are predicted: (i) zero-mean oscillations of T(t) accelerate AD (pumping effect), (ii) the combination of temporal and spatial variations of temperature may lead to superballistic AD, (iii) various forms of T(t, r) may result in non-algebraic AD including exponential diffusion. One can expect similar effects in inflationary systems with time-dependent metric and in expanding/contracting gases.

Recently [P. Varilly, S. Angioletti-Uberti, B. M. Mognetti, and D. Frenkel, “A general theory of DNA-mediated and other valence-limited colloidal interactions,” J. Chem. Phys.137, 094108 (Year: 2012)10.1063/1.4748100], we presented a general theory for calculating the strength and properties of colloidal interactions mediated by ligand–receptor bonds (such as those that bind DNA-coated colloids). In this Communication, we derive a surprisingly simple analytical form for the interaction free energy, which was previously obtainable only via a costly numerical thermodynamic integration. As a result, the computational effort to obtain potentials of interaction is significantly reduced. Moreover, we can gain insight from this analytic expression for the free energy in limiting cases. In particular, the connection of our general theory to other previous specialised approaches is now made transparent. This important simplification will significantly broaden the scope of our theory.

We derive a general formula for the paramagneticNMR nuclear shielding tensor of an open-shell molecule in a pure spin state, subject to a zero-field splitting (ZFS). Our findings are in contradiction with a previous proposal. We present a simple application of the newly derived formula to the case of a triplet ground state split by an easy-plane ZFS spin Hamiltonian. When kT is much smaller than the ZFS gap, thus a single non-degenerate level is thermally populated, our approach correctly predicts a temperature-independentparamagnetic shift, while the previous theory leads to a Curie temperature dependence.

We analyze the performances of the parameter-free hybrid density functional PBE0-1/3 obtained combining the PBE generalized-gradient functional with a predefined amount of exact exchange of 1/3, as recently discussed by Cortona [J. Chem. Phys.136, 086101 (Year: 2012)10.1063/1.3690462]. The numerical results that we have obtained for various properties, such as atomization energies (G2-148 dataset), weak interactions (NCB31 dataset), hydrogen-bond length optimizations, and dissociation energies (HB10 dataset), and vertical excitation energies, show an increased performance of PBE0-1/3 with respect to the widely used PBE0. We therefore propose to use one third as the mixing coefficient for the PBE-based hybrid functional.

The hydroxymethyl peroxy (HMOO) radical is a radical product from the oxidation of non-methane hydrocarbons. The present study provides theoretical prediction of critical spectroscopic features of this radical that should aid in its experimental characterization. Structure, rotational constants, and harmonic frequencies are presented for the ground and first excited electronic states of HMOO. The adiabatic transition energy for the process is 7360 cm−1, suggesting that this transition, occurring in the mid to near infrared, is the most promising candidate for observing the radical spectroscopically. The band origin of the transition of HMOO is calibrated and benchmarked with the corresponding state of the HOO radical, which is experimentally and theoretically well characterized.